Individual/collective self-consumption

The principle of self-consumption involves producing electricity on-site (often via photovoltaics) and consuming it locally at the time it is generated. A distinction is made between individual self-consumption (one producer for a single point of consumption) and collective self-consumption (several producers and consumers sharing energy within a defined area). The challenge is not simply about "installing PV panels": it involves matching production to load profile, reducing the low-value injection of electricity into the grid, and maximizing savings on grid purchases, all while ensuring safety, quality, and effective management.

Self-consumption: operational definition

In individual buildings, the energy directly consumes from its PV panels. The surplus can be sold, stored (battery, domestic hot water tank with heating element, thermal storage) or used remotely through demand response/programming (running certain loads during the day: domestic hot water, enhanced ventilation, non-critical processes). Two key indicators guide the sizing:

• Self-consumption rate: share of PV production consumed on site.
• Self-production rate: share of consumption covered by PV.

In a multi-unit system, consumers (homes, offices, shops) and producers (PV rooftops) pool energy through an allocation scheme and dedicated metering/monitoring. The benefits include smoothing energy consumption patterns (daytime businesses "feed" evening residents), increasing the share of locally consumed energy directly, and stabilizing bills. In both cases, an Energy Management System (EMS) manages batteries and loads, anticipates sunlight, prioritizes storage and injection, and tracks KPIs (self-consumption, self-heating, savings, CO₂ avoided).

Advantages, limitations and points to consider regarding self-consumption

Interests

• Reduced network purchases and better invoice predictability.
• Visible decarbonization (local, traceable electricity).
• Partial resilience with compatible storage and inverters.
• Property enhancement (active roofs, positive image).
• In collective settings: proliferation of profiles → higher self-consumption rates.

Boundaries

• CAPEX (PV, inverters, possibly batteries) to be amortized.
• Weather variability → need for careful sizing.
• Returns and lifespans to be included in the business plan.
• In collective agreements: more complex contractual framework and metrology (counting, allocation rules, governance).

Points to consider

• Electrical safety: protections, disconnectors, lockout/tagout.
• Quality of integration: shading, orientation, ventilation of modules.
• Load management: DHW programmed during the day, HVAC/cooling can be shifted.
• GTB/EMS coupling: scenarios, forecasts, arbitrage thresholds.
• Maintenance: cleaning modules, monitoring inverters/batteries.
• Pricing options: contracted power, time signals, load shedding.

Anecdote — “The morning crescent that lights up the evening”

In a mixed-use building with a bakery on the ground floor, offices on the first floor, and apartments above, the rooftop solar panels produced a lot of energy… when the apartments were empty. By switching to collective self-consumption, the morning's solar energy was first used by the bakery and offices, and then the surplus was allocated to the apartments (domestic hot water controlled during the day + a small storage system for lighting the common areas). The result: increased self-consumption, decreased grid injection, and an amused building manager: "Here, it's the croissants that recharge the water heater." Proof that sometimes, a well-balanced mix of uses is worth more than just another array of panels.